Improvements To AMBA AXI4 Adapters

src/main/scala/amba/axi4/Deinterleaver.scala

@@ -9,38 +9,61 @@ import freechips.rocketchip.config.Parameters
 import freechips.rocketchip.diplomacy._
 import freechips.rocketchip.util.leftOR
 
+/** This adapter deinterleaves read responses on the R channel.
+  *
+  * Deinterleaving guarantees that once the first beat of a read response
+  * has been accepted by the recipient, all further presented read responses will
+  * be from the same burst transaction, until the burst is complete.
+  *
+  * @param maxReadBytes is the maximum supported read burst size that this adapter
+  *   has been provisioned to support.
+  * @param buffer is the internal buffering to provide in the case where no deinterleaving is required.
+  */
 class AXI4Deinterleaver(maxReadBytes: Int, buffer: BufferParams = BufferParams.default)(implicit p: Parameters) extends LazyModule
 {
-  require (maxReadBytes >= 1 && isPow2(maxReadBytes))
+  require (maxReadBytes >= 1, s"AXI4Deinterleaver: maxReadBytes must be at least 1, not $maxReadBytes")
+  require (isPow2(maxReadBytes), s"AXI4Deinterleaver: maxReadBytes must be a power of two, not $maxReadBytes")
 
-  val node = AXI4AdapterNode(
+  private def maxBeats(slave: AXI4SlavePortParameters): Int =
+    (maxReadBytes+slave.beatBytes-1) / slave.beatBytes
+
+  // Nothing to do if R channel only uses a single beat
+  private def nothingToDeinterleave(slave: AXI4SlavePortParameters): Boolean =
+    maxBeats(slave) <= 1
+
+  val node = new AXI4AdapterNode(
     masterFn = { mp => mp },
     slaveFn  = { sp => sp.copy(slaves = sp.slaves.map(s => s.copy(
       supportsRead = s.supportsRead.intersect(TransferSizes(1, maxReadBytes)),
       interleavedId = Some(0))))
-  })
+  }) {
+    override def circuitIdentity = edges.out.map(_.slave).forall(nothingToDeinterleave)
+  }
 
   lazy val module = new LazyModuleImp(this) {
     (node.in zip node.out) foreach { case ((in, edgeIn), (out, edgeOut)) =>
       val endId = edgeOut.master.endId
-      val beatBytes = edgeOut.slave.beatBytes
-      val beats = (maxReadBytes+beatBytes-1) / beatBytes
+      val beats = maxBeats(edgeOut.slave)
 
-      // This adapter leaves the control + write paths completely untouched
+      // This adapter passes through the AR/AW control + W/B write data channels
       out.ar :<> in.ar
       out.aw :<> in.aw
       out.w :<> in.w
       in.b :<> out.b
 
-      if (beats <= 1) {
-        // Nothing to do if only single-beat R
+      // Only the R channel has the possibility of being changed
+      if (nothingToDeinterleave(edgeOut.slave)) {
         in.r.asInstanceOf[ReadyValidIO[AXI4BundleR]] :<> buffer.irrevocable(out.r)
       } else {
+        // We only care to deinterleave ids that are actually in use
+        val maxFlightPerId = Seq.tabulate(endId) { i =>
+          edgeOut.master.masters.find(_.id.contains(i)).flatMap(_.maxFlight).getOrElse(0)
+        }
+
         // Queues to buffer R responses
-        val qs = Seq.tabulate(endId) { i =>
-          val depth = edgeOut.master.masters.find(_.id.contains(i)).flatMap(_.maxFlight).getOrElse(0)
-          if (depth > 0) {
-            val q = Module(new Queue(out.r.bits.cloneType, beats))
+        val qs = maxFlightPerId.zipWithIndex.map { case (mf, i) =>
+          if (mf > 0) {
+            val q = Module(new Queue(out.r.bits.cloneType, entries = beats))
             q.suggestName(s"queue_${i}")
             q.io
           } else {
@@ -63,11 +86,9 @@ class AXI4Deinterleaver(maxReadBytes: Int, buffer: BufferParams = BufferParams.d
         val enq_OH = UIntToOH(enq_id, endId)
 
         // Track the number of completely received bursts per FIFO id
-        val pending = Cat(Seq.tabulate(endId) { i =>
-          val depth = edgeOut.master.masters.find(_.id.contains(i)).flatMap(_.maxFlight).getOrElse(0)
-          if (depth == 0) {
-            false.B
-          } else {
+        val pending = Cat(maxFlightPerId.zipWithIndex.map {
+          case (0, _) => false.B // any id not in use
+          case (_, i) => {       // i is an id in use
             val count = RegInit(0.U(log2Ceil(beats+1).W))
             val next = Wire(chiselTypeOf(count))
             val inc = enq_OH(i) && out.r.fire() && out.r.bits.last

src/main/scala/amba/axi4/IdIndexer.scala

@@ -10,9 +10,17 @@ import freechips.rocketchip.util._
 case object AXI4ExtraId extends ControlKey[UInt]("extra_id")
 case class AXI4ExtraIdField(width: Int) extends SimpleBundleField(AXI4ExtraId)(UInt(OUTPUT, width = width), UInt(0))
 
+/** This adapter limits the set of FIFO domain ids used by outbound transactions.
+  *
+  * Extra AWID and ARID bits from upstream transactions are stored in a User Bits field called AXI4ExtraId,
+  * which values are expected to be echoed back to this adapter alongside any downstream response messages,
+  * and are then prepended to the RID and BID field to restore the original identifier.
+  *
+  * @param idBits is the desired number of A[W|R]ID bits to be used
+  */
 class AXI4IdIndexer(idBits: Int)(implicit p: Parameters) extends LazyModule
 {
-  require (idBits >= 0)
+  require (idBits >= 0, s"AXI4IdIndexer: idBits must be > 0, not $idBits")
 
   val node = AXI4AdapterNode(
     masterFn = { mp =>
@@ -29,19 +37,19 @@ class AXI4IdIndexer(idBits: Int)(implicit p: Parameters) extends LazyModule
       mp.masters.foreach { m =>
         for (i <- m.id.start until m.id.end) {
           val j = i % (1 << idBits)
-          val old = masters(j)
+          val accumulated = masters(j)
           names(j) += m.name
-          masters(j) = old.copy(
-            aligned   = old.aligned && m.aligned,
-            maxFlight = old.maxFlight.flatMap { o => m.maxFlight.map { n => o+n } })
+          masters(j) = accumulated.copy(
+            aligned   = accumulated.aligned && m.aligned,
+            maxFlight = accumulated.maxFlight.flatMap { o => m.maxFlight.map { n => o+n } })
         }
       }
-      names.foreach { n => if (n.isEmpty) n += "(unused)" }
+      val finalNameStrings = names.map { n => if (n.isEmpty) "(unused)" else n.toList.mkString(", ") }
       val bits = log2Ceil(mp.endId) - idBits
       val field = if (bits > 0) Seq(AXI4ExtraIdField(bits)) else Nil
       mp.copy(
         echoFields = field ++ mp.echoFields,
-        masters    = masters.zipWithIndex.map { case (m,i) => m.copy(name = names(i).toList.mkString(", "))})
+        masters    = masters.zip(finalNameStrings).map { case (m, n) => m.copy(name = n) })
     },
     slaveFn = { sp => sp
     })

src/main/scala/amba/axi4/UserYanker.scala

@@ -8,6 +8,14 @@ import freechips.rocketchip.config.Parameters
 import freechips.rocketchip.diplomacy._
 import freechips.rocketchip.util._
 
+/** This adapter prunes all user bit fields of the echo type from request messages,
+  * storing them in queues and echoing them back when matching response messages are recevied.
+  *
+  * It also optionally rate limits the number of transactions that can be in flight simultaneously
+  * per FIFO domain / A[W|R]ID.
+  *
+  * @param capMaxFlight is an optional maximum number of transactions that can be in flight per A[W|R]ID.
+  */
 class AXI4UserYanker(capMaxFlight: Option[Int] = None)(implicit p: Parameters) extends LazyModule
 {
   val node = AXI4AdapterNode(

src/main/scala/tilelink/ToAXI4.scala

@@ -23,16 +23,32 @@ case class AXI4TLStateField(sourceBits: Int) extends BundleField(AXI4TLState) {
   }
 }
 
-class TLtoAXI4IdMap(tl: TLMasterPortParameters, axi4: AXI4MasterPortParameters) 
-  extends IdMap[TLToAXI4IdMapEntry]
+/** TLtoAXI4IdMap serves as a record for the translation performed between id spaces.
+  *
+  * Its member [axi4Masters] is used as the new AXI4MasterParameters in diplomacy.
+  * Its member [mapping] is used as the template for the circuit generated in TLToAXI4Node.module.
+  */
+class TLtoAXI4IdMap(tlPort: TLMasterPortParameters) extends IdMap[TLToAXI4IdMapEntry]
 {
-  private val axiDigits = String.valueOf(axi4.endId-1).length()
-  private val tlDigits = String.valueOf(tl.endSourceId-1).length()
+  val tlMasters = tlPort.masters.sortBy(_.sourceId).sortWith(TLToAXI4.sortByType)
+  private val axi4IdSize = tlMasters.map { tl => if (tl.requestFifo) 1 else tl.sourceId.size }
+  private val axi4IdStart = axi4IdSize.scanLeft(0)(_+_).init
+  val axi4Masters = axi4IdStart.zip(axi4IdSize).zip(tlMasters).map { case ((start, size), tl) =>
+    AXI4MasterParameters(
+      name      = tl.name,
+      id        = IdRange(start, start+size),
+      aligned   = true,
+      maxFlight = Some(if (tl.requestFifo) tl.sourceId.size else 1),
+      nodePath  = tl.nodePath)
+  }
+
+  private val axi4IdEnd = axi4Masters.map(_.id.end).max
+  private val axiDigits = String.valueOf(axi4IdEnd-1).length()
+  private val tlDigits = String.valueOf(tlPort.endSourceId-1).length()
   protected val fmt = s"\t[%${axiDigits}d, %${axiDigits}d) <= [%${tlDigits}d, %${tlDigits}d) %s%s%s"
-  private val sorted = tl.clients.sortBy(_.sourceId).sortWith(TLToAXI4.sortByType)
 
-  val mapping: Seq[TLToAXI4IdMapEntry] = (sorted zip axi4.masters) map { case (c, m) =>
-    TLToAXI4IdMapEntry(m.id, c.sourceId, c.name, c.supports.probe, c.requestFifo)
+  val mapping: Seq[TLToAXI4IdMapEntry] = tlMasters.zip(axi4Masters).map { case (tl, axi) =>
+    TLToAXI4IdMapEntry(axi.id, tl.sourceId, tl.name, tl.supports.probe, tl.requestFifo)
   }
 }
 
@@ -44,26 +60,10 @@ case class TLToAXI4IdMapEntry(axi4Id: IdRange, tlId: IdRange, name: String, isCa
   val maxTransactionsInFlight = Some(tlId.size)
 }
 
-case class TLToAXI4Node(stripBits: Int = 0, wcorrupt: Boolean = true)(implicit valName: ValName) extends MixedAdapterNode(TLImp, AXI4Imp)(
+case class TLToAXI4Node(wcorrupt: Boolean = true)(implicit valName: ValName) extends MixedAdapterNode(TLImp, AXI4Imp)(
   dFn = { p =>
-    p.clients.foreach { c =>
-      require (c.sourceId.start % (1 << stripBits) == 0 &&
-               c.sourceId.end   % (1 << stripBits) == 0,
-               s"Cannot strip bits of aligned client ${c.name}: ${c.sourceId}")
-    }
-    val clients = p.clients.sortWith(TLToAXI4.sortByType _)
-    val idSize = clients.map { c => if (c.requestFifo) 1 else (c.sourceId.size >> stripBits) }
-    val idStart = idSize.scanLeft(0)(_+_).init
-    val masters = ((idStart zip idSize) zip clients) map { case ((start, size), c) =>
-      AXI4MasterParameters(
-        name      = c.name,
-        id        = IdRange(start, start+size),
-        aligned   = true,
-        maxFlight = Some(if (c.requestFifo) c.sourceId.size else (1 << stripBits)),
-        nodePath  = c.nodePath)
-    }
     AXI4MasterPortParameters(
-      masters    = masters,
+      masters    = (new TLtoAXI4IdMap(p)).axi4Masters,
       requestFields = (if (wcorrupt) Seq(AMBACorruptField()) else Seq()) ++ p.requestFields.filter(!_.isInstanceOf[AMBAProtField]),
       echoFields    = AXI4TLStateField(log2Ceil(p.endSourceId)) +: p.echoFields,
       responseKeys  = p.responseKeys)
@@ -91,7 +91,8 @@ case class TLToAXI4Node(stripBits: Int = 0, wcorrupt: Boolean = true)(implicit v
 // wcorrupt alone is not enough; a slave must include AMBACorrupt in the slave port's requestKeys
 class TLToAXI4(val combinational: Boolean = true, val adapterName: Option[String] = None, val stripBits: Int = 0, val wcorrupt: Boolean = true)(implicit p: Parameters) extends LazyModule
 {
-  val node = TLToAXI4Node(stripBits, wcorrupt)
+  require(stripBits == 0, "stripBits > 0 is no longer supported on TLToAXI4")
+  val node = TLToAXI4Node(wcorrupt)
 
   lazy val module = new LazyModuleImp(this) {
     (node.in zip node.out) foreach { case ((in, edgeIn), (out, edgeOut)) =>
@@ -102,15 +103,15 @@ class TLToAXI4(val combinational: Boolean = true, val adapterName: Option[String
       slaves.foreach { s => require (s.interleavedId == slaves(0).interleavedId) }
 
       // Construct the source=>ID mapping table
-      val map = new TLtoAXI4IdMap(edgeIn.client, edgeOut.master)
+      val map = new TLtoAXI4IdMap(edgeIn.client)
       val sourceStall = Wire(Vec(edgeIn.client.endSourceId, Bool()))
       val sourceTable = Wire(Vec(edgeIn.client.endSourceId, out.aw.bits.id))
       val idStall = Wire(init = Vec.fill(edgeOut.master.endId) { Bool(false) })
       var idCount = Array.fill(edgeOut.master.endId) { None:Option[Int] }
 
-      Annotated.idMapping(this, map.mapping).foreach { case TLToAXI4IdMapEntry(axi4Id, tlId, _, _, fifo) =>
+      map.mapping.foreach { case TLToAXI4IdMapEntry(axi4Id, tlId, _, _, fifo) =>
         for (i <- 0 until tlId.size) {
-          val id = axi4Id.start + (if (fifo) 0 else (i >> stripBits))
+          val id = axi4Id.start + (if (fifo) 0 else i)
           sourceStall(tlId.start + i) := idStall(id)
           sourceTable(tlId.start + i) := UInt(id)
         }

src/main/scala/util/Annotations.scala

@@ -10,7 +10,6 @@ import firrtl.annotations._
 
 import freechips.rocketchip.diplomacy._
 import freechips.rocketchip.regmapper._
-import freechips.rocketchip.tilelink.TLToAXI4IdMapEntry
 
 import org.json4s.JsonDSL._
 import org.json4s.jackson.JsonMethods.{pretty, render}
@@ -64,11 +63,6 @@ case class AddressMapAnnotation(target: Named, mapping: Seq[AddressMapEntry], la
       "\n  ]\n}"
 }
 
-/** Record a conversion of TL source ids to AXI4 ids. */
-case class TLToAXI4IdMapAnnotation(target: Named, mapping: Seq[TLToAXI4IdMapEntry]) extends SingleTargetAnnotation[Named] {
-  def duplicate(n: Named) = this.copy(n)
-}
-
 /** Marks this module as a candidate for register retiming */
 case class RetimeModuleAnnotation(target: ModuleName) extends SingleTargetAnnotation[ModuleName] {
   def duplicate(n: ModuleName) = this.copy(n)
@@ -149,11 +143,6 @@ object Annotated {
     mapping
   }
 
-  def idMapping(component: InstanceId, mapping: Seq[TLToAXI4IdMapEntry]): Seq[TLToAXI4IdMapEntry] = {
-    annotate(new ChiselAnnotation { def toFirrtl = TLToAXI4IdMapAnnotation(component.toNamed, mapping) })
-    mapping
-  }
-
   def port[T <: Data](
     data: T,
     protocol: String,